1. Field of the Invention
The present invention relates to a ladder diagram monitoring device, and in particular, relates to a ladder diagram monitoring device on which an operation situation of a ladder program and an operation situation of a CNC can be simultaneously checked.
2. Description of the Related Art
FIG. 7 shows a display example of a ladder program including circuit comments.
In general, when a ladder program executable by a programmable controller is debugged and diagnosed, icons of contacts and coils are displayed on a ladder diagram monitor display screen and display modes of the icons are changed (in FIG. 7, the contacts and the coils whose signal states are ON are presented as enclosed by dotted frames) to thereby display the signal states of a ladder circuit, and annotations of the ladder circuit as circuit comments.
As a prior art for checking operation of the ladder program, there is known a technique in which states of signals used in a ladder program, related signals designated, and parameter values of functional commands are simultaneously displayed with a ladder diagram monitor display function, for example, in Japanese Patent Laid-Open No. 08-123515. Using the technique, debugging of the ladder program of the programmable controller can be facilitated.
Moreover, there are also known techniques in which in a ladder program constituted of a plurality of ladder circuits, a comment explaining the processing content of a specific ladder circuit among those circuits (circuit comment) is displayed in the vicinity of the ladder circuit, in Japanese Patent Laid-Open No. 05-250014 and Japanese Patent Laid-Open No. 2011-107810. These techniques help a user in understanding the ladder circuits.
In a CNC (numerical controller) including a programmable controller built therein, the CNC and the ladder program cooperate with each other to perform control operations; for example, the ladder program is used to control a numerically controlled axis, or the ladder program controls an external device based on an instruction from an NC program. When such a ladder program which cooperatively works with the CNC is debugged and diagnosed, it is also often required to check related operation situations of the CNC in addition to states of signals and values of parameters which are used in the ladder circuit.
Nevertheless, since a screen on which the operation situations of the CNC can be checked is typically a different screen from a screen for the ladder diagram monitor display function, the screens need to be switched individually to view the information for checking the information on both screens. In this case, the information on both screens cannot be simultaneously checked, and there can also be a case where the debugging and the diagnosis are difficult.
There is in sometime cases provided a function of displaying information on the operation situations of the CNC in addition to the ladder diagram monitor display. However, since information of the CNC needed in debugging and diagnosing is different depending on the ladder circuit, the information of the CNC to be displayed has to be reselected individually for the particular ladder circuit to be debugged and diagnosed.